This set of Cell Biology Multiple Choice Questions & Answers (MCQs) focuses on “Techniques – Polymerase Chain Reaction”.
1. Bacteriophage Lambda is a major cloning vector.
Explanation: Bacteriophages are viruses that infect bacterial cells. Bacteriophage lambda genome is linear and double-stranded and of the size of 50 kb in length.it is an important cloning vector.
2. Polymerase chain reaction (PCR) was invented by ______________________
a) Kary Mullis
b) James Watson
c) John Hopkins
d) Hargobind Khorana
Explanation: Polymerase chain reaction (PCR) was conceived in 1983 by Kary Mullis of Cetus Corporation. This technique is widely used for the amplification of DNA sequences without the need for bacterial cells.
3. Taq polymerase is a ________________________ polymerase.
Explanation: Taq polymerase used in the important technique of polymerase chain reaction is a polymerase isolated from the Thermus aquaticus, a bacterium that lives in the hot springs.
4. The temperature cycles in a polymerase chain reaction are in the order __________________
a) 95°, 60°, 72°
b) 60°, 72°, 95°
c) 72°, 60°, 95°
d) 95°, 72°, 60°
Explanation: Three different temperatures are reached during the polymerase chain reaction to facilitate the denaturation and hybridization of the DNA strands. First the temperature is elevated to 95°C, then lowered to 60°C and then again increased to 72°C.
5. Which enzyme is active at 72° in the polymerase chain reaction?
Explanation: Taq polymerase, derived from the thermophilic bacteria Thermus aquaticus is active at 72°. The enzyme is responsible for synthesizing the complementary DNA strand by adding nucleotides to the 3’ end of the primers.
6. PCR can generate large amounts of DNA.
Explanation: Polymerase chain reaction (PCR) can generate large amounts of DNA, even from minuscule samples by amplifying the DNA material present in a single cell. PCRs are also used in crime investigations.
7. Molecular beacons are short ____________________
Explanation: Molecular beacons are short reporter oligonucleotides that have a fluorochrome and a quencher molecule attached to opposite ends. The molecular beacons hybridize in the middle of the sequence to be amplified.
8. When was the nucleotide sequence of a viral genome first elucidated?
Explanation: The first nucleotide sequence of an entire viral genome X174 was sequenced in vitro in the year 1977. The nucleotide sequence contained 5375 nucleotides. Frederick Sanger was the first person to sequence a polypeptide.
9. DNA libraries are collection of ______________________
a) ribonucleic acid
b) cloned DNA fragments
d) viral particles
Explanation: DNA libraries are a collection of cloned DNA fragments; there are two types of DNA libraries namely genomic libraries and complementary-DNA libraries. The libraries are instrumental for genetic researchers.
10. cDNA libraries are produced from ______________________
a) ribonucleic acids
b) messenger RNAs
c) transfer RNAs
d) ribosomal RNAs
Explanation: Complementary DNA (cDNA) libraries are produced from the messenger RNA molecules and represent the type of genes residing in a particular type of cell. The other type of DNA libraries is the genomic library.
11. The endonuclease HaeIII recognizes ______________________ sequence.
Explanation: The endonuclease HaeIII and Sau3A, are tetranucleotide sequences used in the construction of genomic DNA libraries. After digestion of the nucleotides, the fragments are separated by gel electrophoresis.
12. Which of the following can be used to clone DNA sequence of size larger than 25 kb?
a) Yeast artificial chromosome
Explanation: For cloning DNA sequences of a size larger than 20 to 25 kb, the conventional vectors such as plasmids and bacteriophages can not be used. For the cloning of large DNA fragments, the yeast artificial chromosome (YAC) may be used.
13. Bacterial artificial chromosomes are the __________________ of bacterial cells.
a) Polymerase enzyme
Explanation: Bacterial artificial chromosomes are cloning vectors that accept up to 500 kb of DNA. These are specialized plasmids (F-factors) of the bacterial cells that contain bacterial origin of replication.
14. Viral-mediated gene transfer is called _______________
Explanation: Viral-mediated gene transfer is called transduction. In this process a non-replicating virus is allowed to infect a cell population which leads to the expression of gene of interest transiently.
15. The process of introducing DNA into cells is called ____________________
Explanation: The process of introducing DNA into cells without the aid of any cloning vector is termed as transfection. Calcium phosphate or DEAE-dextran can be used for the adherence of foreign DNA to the surface of target cells.
Sanfoundry Global Education & Learning Series – Cell Biology.
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